Thomas Aquinas

“ And as we ascribe to God the power of creating, so we may ascribe the power of begetting and of spirating. But "to understand" and "to will" are not such actions as to designate the procession of something distinct from God, either essentially or personally. Wherefore, with regard to these actions we cannot ascribe power to God in its proper sense, but only after our way of understanding and speaking: inasmuch as we designate by different terms the intellect and the act of understanding in God, whereas in God the act of understanding is His very essence which has no principle. ”

“ The will of God gave to all creatures their substance: but perfect birth gave the Son a nature derived from a substance impassible and unborn. All things created are such as God willed them to be; but the Son, born of God, subsists in the perfect likeness of God. ”

“ Power therefore exists in God regarding the notional acts.
I answer that, As the notional acts exist in God, so must there be also a power in God regarding these acts; since power only means the principle of act. ”

“ Further, God the Father has greater power to beget than has a created father. But a man can beget several sons. Therefore God can also: the more so that the power of the Father is not diminished after begetting the Son. ”

“ Or the mention of wisdom as both created and begotten insinuates into our minds the mode of the divine generation; for in generation what is generated receives the nature of the generator and this pertains to perfection; whereas in creation the Creator is not changed, but the creature does not receive the Creator's nature. Thus the Son is called both created and begotten, in order that from the idea of creation the immutability of the Father may be understood, and from generation the unity of nature in the Father and the Son. ”

“ Nevertheless we cannot speak of divine and intelligible things except after the manner of sensible things, whence we derive our knowledge, and wherein actions and passions, so far as these imply movement, differ from the relations which result from action and passion, and therefore it was necessary to signify the habitudes of the persons separately after the manner of act, and separately after the manner of relations. ”

“ Hence, if we take away movement, action implies nothing more than order of origin, in so far as action proceeds from some cause or principle to what is from that principle. Consequently, since in God no movement exists, the personal action of the one producing a person is only the habitude of the principle to the person who is from the principle ”

“ It would seem that a notional act can be directed to several Persons, so that there may be several Persons begotten or spirated in God. For whoever has the power of begetting can beget. But the Son has the power of begetting. Therefore He can beget. But He cannot beget Himself: therefore He can beget another son. Therefore there can be several Sons in God. ”

“ Divine perfection and the total absence of matter in God require that there cannot be several Sons in God, as we have explained. Wherefore that there are not several Sons is not due to any lack of begetting power in the Father. ”

“ Possible, as opposed to what is necessary, is a consequence of a passive power, which does not exist in God. Hence, in God there is no such thing as possibility in this sense, but only in the sense of possible as contained in what is necessary ”

“ Hence action, in its primary sense, means origin of movement; for, as movement derived from another into a mobile object, is called "passion," so the origin of movement itself as beginning from another and terminating in what is moved, is called "action." ”

“ For since the divine Persons are the relations themselves as subsistent, there would not be several Fathers, or several Sons in God, unless there were more than one paternity, or more than one filiation. ”

“ What this power means?
(6) Whether several persons can be the term of one notional act?
Art. 1 - Whether the notional acts are to be attributed to the persons? Objection 1: It would seem that the notional acts are not to be attributed to the persons. For Boethius says (De Trin.) : "Whatever is predicated of God, of whatever genus it be, becomes the divine substance, except what pertains to the relation." But action is one of the ten "genera." Therefore any action attributed to God belongs to His essence, and not to a notion. ”